By law, houses must be built with fireproof (ie. Brick) walls between them, so a fire will not spread from one house to the next. This gives them a distinctive look [1].

There are no timber frame buildings, not any with flammable roofs like thatch or shingles.

They aren't going to make the mistakes of the great fire again!

It seems to work - I have never seen any fire burn more than one building.

[1]: https://www.reddit.com/r/london/comments/149wg3o/why_do_lond...